linux-kernel - Re: [RESEND PATCH 2/4] x86: add phys addr validity check for /dev/mem mmap

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Date:	Tue, 30 Sep 2014 14:41:22 +0200
From:	Frantisek Hrbata <fhrbata@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, oleg@...hat.com,
	kamaleshb@...ibm.com, hechjie@...ibm.com,
	akpm@...ux-foundation.org, dave.hansen@...el.com,
	dvlasenk@...hat.com, prarit@...hat.com, lwoodman@...hat.com,
	hannsj_uhl@...ibm.com, torvalds@...ux-foundation.org
Subject: Re: [RESEND PATCH 2/4] x86: add phys addr validity check for
 /dev/mem mmap

On Mon, Sep 29, 2014 at 10:15:28PM +0200, Thomas Gleixner wrote:
> On Mon, 29 Sep 2014, Frantisek Hrbata wrote:
> > V2: fix pfn check in valid_mmap_phys_addr_range, thanks to Dave Hansen
> 
> AFAICT, Dave also asked you to change size_t count into something more
> intuitive, i.e. nr_bytes or such.

Hi,

mea culpa, I for unknown reason changed it from "size" to "count". I guess some
cut&paste mess. The correct prototype used elsewhere in kernel is

int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)

Does it make sense to replace "count" with "size" so it's consistent with the
rest or do you prefer "nr_bytes" or as Dave proposed "len_bytes"?

I will fix this and I'm sorry Dave I did not change it as discussed. It totally
slipped my mind.

Many thanks Thomas.

> 
> > +int valid_mmap_phys_addr_range(unsigned long pfn, size_t count)
> 
> And right he is. I really had to look twice to see that count is
> actually number of bytes and not number of pages, which is what you
> expect after pfn.
> 
> > +{
> > +	return arch_pfn_possible(pfn + (count >> PAGE_SHIFT));
> > +}
> 
> Thanks,
> 
> 	tglx

-- 
Frantisek Hrbata
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